SAE J1939 Stack Layers

Hardware Abstraction Layer (Physical Layer, OSI Layer 1). The HAL is completely dependant upon the physical CAN hardware selected. Included are instructions for developing new HAL and linking it to the Data Link Layer.
Data Link Layer (OSI Layer 2). The CAN controller chip implements most of the data link layer; however some tasks are required of the microcontroller program such as assembly of the CAN ID from data elements (and corresponding disassembly into data elements from CAN ID). Note that J1939 only supports extended CAN data frames.
Transport Layer (OSI Layer 4). A complex layer containing algorithms to receive and transmit J1939 transport protocol messages. Both Broadcast Announce Messaging (TP-BAM) and Connection Management (TP-CM) are supported.
Network Management Layer. Supports all the required J1939 network management functions e.g. Address Claim and Address Request. The type of device that you are developing will have some effect on how this layer functions. J1939/81 defines the different types of devices and how they operate on the network.